Progressive Multifocal Leukoencephalopathy Presenting as Primary CNS Malignancy in an Immunocompetent Patient

Area of Science:

• Neurology
• Infectious Diseases
• Oncology

Background:

• Progressive multifocal leukoencephalopathy (PML) is a rare, opportunistic infection caused by the John Cunningham virus (JCV).
• PML typically affects immunocompromised individuals, presenting with diverse neurological deficits.
• Differential diagnosis of PML can be challenging, often overlapping with primary central nervous system (CNS) tumors.

Observation:

• A 74-year-old male presented with progressive memory loss, confusion, and aphasia over six weeks.
• Brain MRI and spectroscopy suggested primary CNS lymphoma or diffuse glioma.
• Stereotactic brain biopsy revealed findings suggestive of viral infection, confirmed as PML by JCV DNA in-situ hybridization (ISH).

Findings:

• The patient was diagnosed with PML, initially misdiagnosed as CNS lymphoma.
• JCV DNA in-situ hybridization (ISH) was crucial for confirming the PML diagnosis.
• The patient's neurological condition improved spontaneously without specific antiviral treatment.

Implications:

• This case represents the first reported instance of primary PML presenting as CNS lymphoma in contemporary medical literature.
• Highlights the importance of considering infectious etiologies, including PML, in the differential diagnosis of CNS lesions.
• Emphasizes the diagnostic utility of JCV DNA ISH in complex neurological cases.